Researchers find bifunctional antibiotic

Sean F. Brady and co-authors reported a bifunctional antibiotic called cilagicin after using bioinformatic prospecting to identify a previously uncharacterized bacterial gene cluster and then chemically synthesize the compound. The work, published in Science in May 2022 and recirculated in science threads on May 24, described cilagicin as a lipopeptide antibiotic with low apparent resistance potential in laboratory testing. The study said the compound inhibited gram-positive bacteria, including multidrug-resistant clinical isolates, and acted through two linked targets in cell-wall biosynthesis. The social posts circulating Sunday pointed readers to the paper’s computational methods and supporting datasets, but did not cite any human clinical trial results. ### Which researchers reported the finding, and where did it appear? Zongqiang Wang, Bimal Koirala, Yozen Hernandez, Matthew Zimmerman and Sean F. Brady were listed as authors on the Science paper, “Bioinformatic prospecting and synthesis of a bifunctional lipopeptide antibiotic that evades resistance.” Science published the paper online on May 26, 2022, according to the journal record and mirrored indexing pages. Columbia University chemist Brady’s group said the compound was not isolated through a conventional culture-first screen. (science.org) Instead, the team searched bacterial genome data for biosynthetic gene clusters that might encode overlooked antibiotics, then used the predicted chemistry to make the molecule in the lab. EurekAlert’s release on the paper described the approach as bioinformatic prospecting followed by synthesis of a naturally inspired compound. ### What makes cilagicin “bifunctional”? Science said cilagicin sequesters two distinct undecaprenyl phosphate molecules that bacteria need for cell-wall construction. Europe PMC’s summary of the paper said those two molecules are “indispensable” to cell-wall biosynthesis, which is why the authors argued the antibiotic had a lower chance of selecting resistance through a single mutational change. The paper framed that dual engagement as the key mechanistic feature. (eurekalert.org) Rather than hitting one protein target, cilagicin interacts with two lipid carriers involved in building the bacterial envelope, giving the compound what the authors called a bifunctional mode of action. ### What evidence did the paper give on resistance? The 2022 study reported no detectable resistance in laboratory tests and among the multidrug-resistant clinical isolates examined by the researchers. (europepmc.org) EurekAlert’s summary said the compound showed “low resistance potential,” while the paper’s abstract and indexing summaries used stronger phrasing, saying the antibiotic “evades resistance” in the reported experiments. The evidence in the public record is preclinical. (science.org) The paper and supplementary materials describe microbiology, synthesis and mechanistic studies, but the sources reviewed here do not report human efficacy data, dosing in patients or clinical trial enrollment. ### How was the antibiotic found from sequence data instead of a petri dish? The Science paper said the researchers began with uncharacterized biosynthetic gene clusters found in bacterial genome-sequencing datasets. (eurekalert.org) The team used those genomic signatures to predict a class of calcium-dependent antibiotics and then synthesized candidate structures to test for activity. Supplementary materials linked from Science provide the computational and experimental workflow behind that process, including the bioinformatic analysis of the cil gene cluster and the downstream chemistry. (science.org) That is the material amplified in Sunday’s science threads pointing readers to methods and datasets rather than to new clinical data. ### What should readers be careful not to overstate? May 24 social posts described the finding as a novel bifunctional antibiotic with low resistance potential, but the underlying paper is from 2022, not a newly posted preprint on Sunday. (science.org) The available sources support claims about laboratory inhibition, mechanism and resistance testing; they do not support claims that the drug has succeeded in human trials. Science and its supplementary files remain the main public sources for the work, with author names, methods and mechanistic data available there for readers who want the primary record. (science.org 1) (science.org 2)